The purpose of this study was to compare the degree of axonal regeneration between end-to-end and terminolateral neurorrhaphy, and determine the degree of nerve regeneration for each method of terminolateral neurorrhaphy.

Thirty-two Sprague-Dawley rats (N=64) were divided into four experimental groups: End-to-end neurorrhaphy (Group 1), end-to-side neurorrhaphy without removal of the epineurial sheath (Group 2), with an epineurial window (Group 3), and with an epineurial window combined with tibial motor axonotomy (Group 4). Each group were sacrificed after needle electromyography at 2, 4, 8, and 12 weeks and transmission electron microscopy was performed to observe the histologic findings of coaptation sites. The weights of tibialis anterior muscles were measured.

The amplitude of the compound motor action potential was always lowest in group 4, and there was no statistically significant difference between groups 2 and 3 in terms of the ratio of myelinated to non-myelinated nerve fiber. However, there was a statistically significant difference between groups 2 and 3 in terms of the thickness of the myelin sheath. The tibialis anterior muscle weight in Group 1 increased more so than in the other groups and there was statistically significant difference between group 1 and 4.

End-to-end neurorrhaphy is the best method of nerve repair, and there was no statistically significant difference between epineurial and epineurial window coaptation in end-to-side neurorrhapy.